Castering wheel



Sept. 1939. A. KANTRCSWITZ CASTERING WHEEL Filed Nov. 29, 1937 2 Sheets-Sheet 1 INVENTOR ARTHUR KANTROWITZ BY r w J Ill-7 ATTORNEY Sept. 12, 1939.. A. KANTROWITZ CASTERING WHEEL Filed NOV. 29, 1937 2 Sheets-Sheet 2 m I i 2 a II 3 6 Fly. 4.

INVENTOR A RTHUR KANTROW/ TZ ATTORNEY Patented Sept. 12, 1939 UNITED STATES PATENT OFFICE 11 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This invention relates to castering wheels and it has particular relation to castering wheels for aircraft and other vehicles.

Heretofore, one of the objections to castering wheels has been the tendency for them to oscillate or shimmy. This shimmy is a self-excited oscillation occurring in elastic or rubber tired castering wheels and produced in the following manner: Let it be supposed that the wheel is set at an angle to the direction of motion of the vehicle by an irregularity in the ground. If the tire does not skid when the vehicle moves forward, the bottom must deflect laterally, since there is a component of motion in this direction. Considering the vehicle to be still moving forward slowly, when the tire has deflected laterally it will tend to straighten the wheel. When this has occurred,

the tire will still be deflected and consequently,

the wheel continues to turn and eventually over- 20 shoots until it finally reaches an angle approximately equal and opposite in sign to the original angle at which the wheel was set. This effect is repeated and the oscillations continue at approximately the same amplitude as long as the vehicle moves slowly. If the vehicle should move more rapidly, the oscillations will occur morefrequently and the moment of inertia about the castering spindle causes an appreciable inertia torque. This inertia torque makes the angle of the wheel lag behind the phase relationship to the deflection of the tire which it formerly had and gives the tire more time to deflect. Thus, the tirevdeflects more than before and on the next one-half cycle the wheel turns further with the result that energy is continually fed into the oscillation. This energy input is frequently sufllcient to overcome whatever energy losses may be present in the system. When this occurs the oscillations increase in amplitude and may impose severe oscillatory loads on the vehicle. Thus, it will be apparent that the interaction of lateral deflection of the tire with the angular or rotary spindle motion is the cause of the shimmy.

One of the objects of the present invention is to prevent the objectionable shimmy above explained by providing a construction in which the wheel is permitted to move a limited distance laterally relative to the axis of the castering spindle. Thus the tire deflection is partially neutralized continually and its interaction with the angular motion can be reduced enough to prevent shimmy.

With these and other objects in view, as well as other advantages which may be incident to the use, of the improvements, the invention consists of the parts and combinations thereof herein-. after set forth and claimed, with the understanding that the several necessary elements constituting the same may be varied in proportion and arrangement without departing from thenature 5 and scope of the invention as defined in the appended claims. i

. In order to make the invention more clearly understood there are shown in the accompanying drawings means for carrying the invention into In practical effect, without limiting the improvements in their useful application to the particular construction, which, for the purpose of explanation, have been made the subject of illustration.

In the accompanying drawings: 1

Fig. 1 is a rear elevational view of a castering wheel constructed in accordance with the invention;

Fig. 2 is a view partly in side elevation and partly in vertical section on line 22 of Fig; 1; 20

Fig. 3 is a transverse sectional View taken on line 3-3 of Fig. 2;

Fig. 4 is a rear elevational view of another form of castering wheel embodying the invention;

Fig. 5 is a view partly in side elevation and 25 partly in vertical section on line 55 of Fig. 4; and

Fig. 6 is a transverse sectional ,view taken on line 6-6 of Fig. 5.

Referring to the drawings, and particularly to at Figs. 1 to 3 thereof, a castering wheel constructed in accordance with the present invention is shown as compriisng a yoke Ill provided with a vertical spindle H which is rotatably mounted by means of step bearings I2 and lateral thrust bearings 35 I3 in a tubular post l4 carried by the fuselage of the aircraft. A shaft [5, preferably square in cross-section, is non-rotatably mounted at its ends in the legs iii of the yoke and curves rearwardly and downwardly to give a crown effect 40 thereto. A wheel I! of any preferred type, is rotatably mounted on bearings l8 (Fig. 3) which are tied together by a bolt 2| and which are slidably mounted on the shaft IS in spaced relation to the legs l6 of the yoke. It willbe ap- 45 parent from this construction that the wheel I1 is free to move laterally on the shaft IS a limited amount without transmitting any motion to the yoke I0 or fuselage, but due to the curvature of the axle there is a constant tendency for the 50 wheel to centralize itself between the legs N5 of the yoke. This free lateral movement of the wheel I! and bearings l8 on the shaft I5 is, however, restrained or dampened by means of braking devices disposed on opposite sides of the wheel. Each of the devices comprises two semicircular shoes I! and 20,,the former being secured to the adjacent bearing II on one side of the shaft I! by means of the bolt 2| which ties the halves ,of bearing I. together, and the latter being adjustably secured to the shoe I! for frictional contact with the shaft I! by bolts 22' having right and left screw threaded ends engaging the shoes l9 and 20 (F18. 2).

In Figs. 4 and there is shown another embodimentof the invention in which the lower end of the spindle II is formed with a pair of i'sp'aced cars 22 and 23 carrying bearings 24 .in

' knuckle joint between the wheel and the spindle for permitting the 'wheel and yoke to swing laterally about the pin 25 as a pivot. This lateral swinging movement is limited by a lug or projection 28 formed on the upper car 22 of the spindle which projects into a slot 29 provided in the upper ear 26 of the yoke. In this construction the wheel is mounted on a straight axle 30 and does not move laterally thereon, as in the structure shown in Figs. 1 to 3.

The rotative movement of the spindle II in the structures shown in all of the figures is pref-' erably restrained by means of a brake of any suitable type herein shown as comprising springs 3| (Fig; 6) arranged on opposite sides of the post II and disposed within a groove or channel 32 formed therein. The springs 3| are held in position and at the desired tension by bolts 33 threaded into the spindle H and projecting through slots 34 formed in the post. The rotative movement of the spindle Ii in all of the figures is limited in any suitable way herein shown as being limited by the bolts 33 abutting the ends of the slots 34.

From the foregoing it will be apparent that by means of the present invention there is provided a castering wheel which, except for the action of the braking means, is freely movable in a lateral direction relatively to the post I, thus, when properly adjusted, eliminating all tendency for the objectionable shimmy" heretofore encountered.

Other modifications and changes in the pro-' portion and arrangement of the parts, other than those shown, may be made by those skilled in the art, without departing from the nature and scope of the invention, as defined in the appended claims.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. A castering wheel for aircraft and other vehicles comprising a spindle adapted to be mounted in a bearing on the aircraft for rotation about an axis disposed in a' substantially longitudinally extending vertical plane; a yoke member carried by said spindle; a downwardly curved axle fixed at its ends in said yoke member; and a castering wheel of less width than said yoke member rotatably mounted on said axle for free'longitudinal movement thereon.

2. A castering wheel for aircraft and other vehicles comprising a spindle adapted to be.

mounted in a bearing on the aircraft for rotation about a.substantially vertical axis; a yoke member carried by said spindle; a rearwardly and downwardly curved axle fixed at its ends in said yoke member; and a castering wheel of less width than said yoke member rotatably mounted on said axle for free longitudinal movement I less width than said yoke member rotatably mounted on said slide bearings, said wheel and bearings being free to move laterally along said axle within said yoke member.

4. A castering wheel for aircraft and other vehicles comprising a spindle adapted to be mounted in abearing on the aircraft for rotation about a substantially vertical axis; a yoke member carwardly curved axle of rectangular cross-section fixed at its ends in said yoke member; nonrotary slide bearings mounted on said axle; and a castering wheel of less'widththan said yoke member rotatably mounted on said slide bearings, said wheel and bearings being free to move laterally along said axle -within said yoke member. v 5. A castering wheel for aircraft and other ve- .ried by said spindle; arearwardly and down-' hicles comprising a spindle adapted to be mounted in a bearing on the aircraft for rotation about. a substantially vertical axis; a yoke member car-. ried bysaid spindle; a rearwardly and downwardly curved axle of rectangular cross-section fixed at its ends in said yoke member; non-rotary slide bearings mounted on said axle; and a castering wheel of less width than said yoke member rotatably mounted on said slidebearings, said wheel and bearings being free to move laterally along said axle within said yoke member.

6. A castering wheel for aircraft and other vehicles comprising a spindle adapted to'be mount ed in a bearing on the aircraft for rotation about a substantially vertical axis; a yoke member carried by said spindle; a downwardly curved axle of rectangular crosssection fixed at its ends in said yoke member; non-rotary slide bearings mounted on said axle; a castering wheel of less width than said yoke member rotatably mounted on said slide bearings, said wheel. and bearings being free to move laterally along said axle with in said yoke member; and means for dampening the lateral movement of said wheel.

'7. A castering 'wheel for aircraft and other vehicles comprising a spindle adapted to be mounted in a bearing on the aircraft for rotation about a substantially vertical axis; a yoke member carried by said spindle; a rearwardly and downwardly curved axle of rectangular cross-section fixed at its ends in said yoke member; non-rotary slide bear ngs mounted on said axle; a castering wheel of less width than said yoke member rotatably mounted on said slide bearings, said wheel and bearings being free to move laterally along-said axle within said yoke member; and means for yieldably opposing the lateral movement of said wheel.

8. A castering wheel for aircraft and other vehicles comprising a yoke member adapted to be mounted on a bearing on the aircraft for rotation'about a substantially vertical axis and for lateral swinging movement about an axis extending at an angle upwardly and rearwardly with respect to the axis of rotation of said yoke member in said bearing, and a Wheel rotatably mounted on said yoke member.

9. A castering wheel for aircraft comprising a spindle adapted to be mounted in a bearing on the aircraft for rotation about a substantially vertical axis; a yoke member mounted on said spindle for lateral swinging movement about an axis extending at an angle upwardly and rearwardly with respect to the axis of rotation of said spindle, a wheel rotatably mounted on said yoke member in said bearing, and means for limiting the lateral swinging movement of said yoke member,

10. A castering wheel for aircraft and other vehicles comprising a. spindle adapted to be mounted in a bearing on the aircraft for rotation about a substantially vertical axis; a yoke member mounted on said spindle for lateral swinging movement about an axis extending at an acute angle upwardly and rearwardly with respect to the axis of rotation of said spindle, and a wheel rotatably mounted on said yoke member.

11. A castering wheel for aircraft and other vehicles comprising a. spindle adapted to be mounted in a bearing on the aircraft for'rotation about a substantially vertical axis; a yoke member mounted on said spindle for lateral swinging movement about an axis extending at an acute angle upwardly and rearwardly with respect to the axis of rotation of said spindle; a wheel rotatably mounted on said yoke member, and means for limiting the lateral swinging movement of said yoke member.

' ARTHUR KANTROWITZ. 

